Biological Molecules

Question 1

What are the four main groups of biological molecules?

Answer 1

Carbohydrates, proteins, lipids (fats) and DNA

Question 2

What are carbohydrates, proteins and lipids all made up of?

Answer 2

Carbon, hydrogen and oxygen

Question 3

What do proteins contain that carbohydrates, proteins and lipids don’t?

Answer 3

Nitrogen and sometimes sulphur

Question 4

What is an organic molecule?

Answer 4

A molecule that contains carbon and hydrogen

Question 5

What are the 2 types of carbohydrates?

Answer 5

Simple sugars and complex carbohydrates

Question 6

What are the characteristics of sugars?

Answer 6

Soluble in water and sweet tasting

Question 7

Name 3 simple sugars

Answer 7

Glucose, lactose, sucrose

Question 8

Name of a single unit of sugar

Answer 8

Monosaccharide

Question 9

Name of 2 sugar molecules joined together

Answer 9

Disaccharide

Question 10

What chemical process do simple sugars supply energy for?

Answer 10

Respiration

Question 11

Complex carbohydrates are made of……….

Answer 11

thousands of glucose molecules

Question 12

What are polymers?

Answer 12

Large molecules made of many repeating monomers

Question 13

Complex carbohydrates are storage molecules, how are they stored in both plants and animals?

Answer 13

Starch in plants, glycogen in animals

Question 14

What are the 3 characteristics of storage molecules?

Answer 14

• Insoluble so won’t affect water movement
• Compact so can store lots of glucose in a small space
• Less reactive than glucose so isn’t broken down

Question 15

Name a complex carbohydrate that makes up plant cell walls

Answer 15

Cellulose

Question 16

What are proteins made up of?

Answer 16

Many amino acids which are joined together

Question 17

How many different amino acids and proteins are there?

Answer 17

20 amino acids and limitless number of proteins

Question 18

What are the 5 functions of proteins?

Answer 18

• structural molecules (collagen/keratin)
• controlling chemical reactions (enzymes)
• messenger molecules (hormones)
• combating disease (antibodies)
• transport (haemoglobin/cell membrane)

Question 19

What are the 5 functions of lipids?

Answer 19

• energy storage
• thermal and electrical insulation
• protection of organs
• make some hormones
• essential part of cell membranes

Question 20

All lipids are made up of which two types of molecules?

Answer 20

Fatty acids and glycerol

Question 21

Saturated fatty acids = ??

Answer 21

FATS, these are solid at room temperature

Question 22

Unsaturated fatty acids = ??

Answer 22

OILS, these are liquid at room temperature

Question 23

Outline the 3 main steps of Benedict’s test for glucose

Answer 23

• Add 5cm cubed of Benedict’s solution to the liquid
• Heat, using a water bath at 60ºC
• If glucose is present = blue to brick red

Question 24

Outline the 2 mains steps of the iodine test for starch

Answer 24

• Add 5-10 drops of iodine solution

- If starch present = brown to blue-black

Question 25

What is a catalyst?

Answer 25

A chemical which increases the rate of a reaction without being used up itself in the reaction

Question 26

What are catabolic reactions?

Answer 26

Breaking down large molecules into smaller products e.g. digestion

Question 27

What are anabolic reactions?

Answer 27

Building large molecules from smaller substrates e.g. DNA synthesis)

Question 28

Explain the Lock and Key theory of how enzymes work

Answer 28

• the substrate binds to the active site of the enzyme
• shape of active site compliments shape of substrate
• the products of the reaction don’t fit the active site as well as the substrate, so they are released

Question 29

What are the benefits of binding to the active site.

Answer 29

• allows lower Ea than without the enzyme
• allows enzymes to increase rate of reaction
• without enzymes = slow reactions, dead organisms